Photographic shutter.



No. 729,015. 7 PATENTED MAY 26, 1903. J. E. THORNTON.

PHOTOGRAPHIG SHUTTER.

APPLICATION FILED DEO.18| 1899.

N0 MODEL.

UNITED STATES Patented May 26, 1903.

PATENT OFFICE.

PHOTOGRAPHIC SHUTTER.

SPECIFICATION forming part of Letters Patent No. 729,015, dated May 26, 1903.

Application filed December 18, 1899- Serial No. 740,833. (No model.)

vented certain new and useful Improvements in Photographic Shutters, of which the following is a specification.

The improvements forming the subject of this invention relate to the mechanism of photographic roller-blind shutters. In these as usually constructed a flexible blind is rapidly moved through the uncoiling of a long coiled-wire spring inclosed in a barrel which forms one of the rollers of the blind or else a volute spring placed in a separate barrel attached to some part of the shutter. If placed in the roller, (as is usual in blind-shutters,) a very long, weak, and flexible spring is sufficient to drive the rollers and rotate them a suificient number of times, while it also allows the extent to which the spring can be wound to be varied very considerably, and thus give the shutter-blind a wide range of speed, and therefore similar range of exposures, all with out great jerk or concussion upon stoppage of the blind. In the other case, of a volute spring, it has been found that the same range of adjustment and flexibility cannot be got, (at any rate in the space usually available,) and while such springs suit some forms of shutters the other form of spring, already described, is much superior for blinds which have a considerable travel.

This invention provides a means of obtaining the advantages of a long coiled spiral spring in a different way for shutters where the construction does not lend itself to the spring being conveniently inclosed in the roller and where the volute form of spring would be unsatisfactory.

The invention will be fully described with reference to the accompanying drawings.

Figure 1 is a front elevation of shutter, showing one arrangement of the invention. Fig. 2 is an end view of shutter, showing the releasing mechanism for the blind.

The blind is driven bya closely-coiled spiral spring of very small diameter and considorable length, which gives motion to the blind by reason of the spring exerting a pull in the direction of its length after having been elongated by the action of winding the blind uponthe opposite roller to that to which the sprin is attached.

The blind A is mounted upon or attached to two rollers B and O, the rotation of either of which in one direction winds the blind A upon it, drawing it at the same time off the other.

In Fig. 1 a long spiral spring D is attached at one end to the shutter-case E and at the other end is attached to a'small worm or pulley b on the spindle of the roller B. The spring D wraps around the worm or pulley b in the reverse direction to that in which the blind A wraps around the roller B. v Consequently as the blind A is unwound the spring is wound up, and thereby elongated, and'vice Versa. A pulley o is placed on the end of the spindle of'the roller 0, around which a cord F is wound in the reverse direction to that in which the blind is wound upon the roller 0. The blind is wound up upon the roller- 0 by the pulling of thecord F and unwinding of it from its pulley c, the same action drawing the blind off the roller B and causing the roller and worm or pulley b to rotate, thereby winding up a length of the spring D, on the worm or pulley b, elongating it and putting it in tension. On the release of the blind A the tension of the spring actuates the roller B and with it the blind A.

The spring-actuated roller B is held against the tension of the long straight spring D when set and released for exposure by a mechanism ofordinary constructiom-such, for example, as shown in Fig. 2, comprisinga disk 0, with stop-pins 0 o, a stop-lever P, and a pneumatic bulbp for raising the lever P out of contact with the pin 0.

What I claim as my invention, and desire to protect by Letters Patent, is-- I 1. In a photographic shutter the combination with the roller-blind A, the rollers B and 0 upon which it is wound, and a spring to actuate the rollers acting in the direction of its longitudinal axis, of a drum aflixed to the reeling-roller, to which one end of the spring is connected and by the rotation of which the spring is elongated and tensified, substantially as described.

2. In a photographic shutter the combination with the roller-blind A, the reeling-roller B, the setting-roller (Land a spring actingin i In witneswhereof I have hereunto signed the direction of its longitudinal axis to oper- I my name in the presence of two subscribing [0 ate the rollers of a spiral drum afiixed to the Witnesses.

reeling-roller to which one end of the sprin L is attached, and in the groove of which n12 JOHN EDWARD THORNTON spring is Wound as the roller is rotated, by Witnesses: the withdrawal of the blind therefrom, sub- J. OWDEN OBRIEN, stantially as described. E. HOWARD. 

